while ( true ) { }

[iOS] Technical Interview possible question – 01

Alberto — Wed, 01 Feb 2012 14:57:26 +0000

Suppose that we have a ViewController.h and .m like this:

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// ViewController.h
#import UIKit/UIKit.h

@interface ViewController : UIViewController
@end

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// ViewController.m
#import "ViewController.h"
#import "SetValue.h"

@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];

[SetValue SetTheValue:@"a string"];
}
@end

And a class called SetValue, with two methods.

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// SetValue.h
#import Foundation/Foundation.h

@interface SetValue : NSObject { }

+ (void) SetTheValue:(id)Obj;
- (void) MySelector:(id)Obj;

@end

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// SetValue.m
#import "SetValue.h"

@implementation SetValue

+ (void) SetTheValue:(id)Obj
{
[self performSelectorOnMainThread:@selector(MySelector:)
withObject:Obj
waitUntilDone:NO];
}

- (void) MySelector:(id)Obj
{
NSLog(@"Data: %@", [Obj description]);
}

@end

What is the value printed by the NSLog?

enjoy.

[Objective-C] NSString and RetainCount

Alberto — Wed, 01 Feb 2012 11:08:44 +0000

NSString and retainCount memo:

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NSString *A = [[NSString alloc] init];
NSLog(@"_A_RC: %i", [A retainCount]);

NSString *B = [[NSString alloc] initWithFormat:@"AAA"];
NSLog(@"_B_RC: %i", [B retainCount]);

NSString *C = [[NSString alloc] initWithString:@"AAA"];
NSLog(@"_C_RC: %i", [C retainCount]);

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...Test[3530:15203] _A_RC: -1 (ios < 5 = 2147483647)
...Test[3530:15203] _B_RC: 1
...Test[3530:15203] _C_RC: -1 (ios < 5 = 2147483647)

Because your string is not in the heap, but is a constant. A NSString made from a constant NSString is identical to the original NSString.

UINT_MAX (2147483647) -> http://it.wikipedia.org/wiki/2147483647

[fun] – How to write good code

Alberto — Wed, 21 Dec 2011 14:12:22 +0000

Mobile Marketing

Alberto — Wed, 21 Dec 2011 14:06:55 +0000

[fun] – How to fix any computer…

Alberto — Wed, 21 Dec 2011 14:01:52 +0000

[fun] – IT organizational charts

Alberto — Wed, 21 Dec 2011 13:57:03 +0000

codesnippet.biz

[fun] – Tempo libero?

Alberto — Wed, 21 Dec 2011 13:42:29 +0000

codesnippet.biz

[Objective-C] Read default Info.plist

Alberto — Wed, 21 Dec 2011 11:45:33 +0000

Reading Info.plist:

1 2	NSBundle* mainBundle = [NSBundle mainBundle]; NSLog(@"%@", [mainBundle objectForInfoDictionaryKey:@"UIBackgroundModes"]);

Writing Info.plist

You can’t.
App bundles are read-only because they are signed, changing their content would break the signing and the app would be considered to be tampered with and not run.

[SHELL] Count lines of code in all files recursively

Alberto — Fri, 16 Dec 2011 15:06:03 +0000

Here a unix command line script to count code lines for your project (or something else!).

In this example it counts lines in an Objective-C iOS Application (.h or .m files).

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$
$find . $ -name '*.h' -o -name '*.m' $ -print -exec cat {} \; | wc -l
25812
$

Explanation:

find . $ -name ‘*.h’ -o -name ‘*.m’ $ -print

- list all files endings with .H or .M recursively from current folder (.).

-exec cat {} \;

- while it finds files, exec a cat on current file

wc -l

- count lines of current file and sum it to total.

25812 lines of code! Sounds good!

enjoy!

Win a Paid GitHub Account!

Alberto — Thu, 15 Dec 2011 23:58:58 +0000

Great idea!
Follow this link: http://appsumo.com/~_z6T and you can win a paid account for Github!
You need only respond to a simple question!

Do you know GitHub.com?

git·hub /’ɡɪtˌhʌb/
GitHub is the best way to collaborate with others. Fork, send pull requests and manage all your public and private git repositories.

Click here http://appsumo.com/~_z6T and Win!

Enjoy!